813 lines
27 KiB
Plaintext
813 lines
27 KiB
Plaintext
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MS-DOS 2.0
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Utility Extensions
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The following notation is used below:
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[item] item is optional.
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item* item is repeated 0 or more times.
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item+ item is repeated 1 or more times.
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{item1 | item2}
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item1 is present or item 2 is present but
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not both.
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<object> indicates a syntactic variable.
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COMMAND invokation
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COMMAND [[<drive>:]<path>] [<cttydev>] [-D] [-P] [-C <string>]
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-P If present COMMAND will be permanent, otherwise
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this is a transient command.
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-D If present COMMAND will not prompt for DATE and
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TIME when it comes up.
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d: Specifies device where command will look for
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COMMAND.COM current default drive if absent.
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<Path> Specifies a directory on device d: root
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directory if absent.
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<cttydev> Name of the CTTY device. /DEV/CON if absent
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and command is permanent. The /DEV/ may be left
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off if AVAILDEV is TRUE (see sysinit doc).
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-C <string> If present -C must be the last switch.
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This causes COMMAND to try to execute the string
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as if the user had typed it at the standard input.
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COMMAND executes this single command string and
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then exits. If the -P switch is present it is
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ignored (can't have a single command, permanent
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COMMAND). NOTE: ALL of the text on the command
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line after the -C is just passed on. It is not
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processed for more arguments, this is why -C must
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be last.
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COMMAND extensions
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IF <condition> <command>
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where <condition> is one of the following:
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ERRORLEVEL <number>
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true if and only if the previous program EXECed by
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COMMAND had an exit code of <number> or higher.
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<string1> == <string2>
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true if and only if <string1> and <string2> are
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identical after parameter substitution. Strings
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may not have embedded delimiters.
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EXIST <filename>
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true if and only if <filename> exists.
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NOT <condition>
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true if and only if <condition> is false.
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The IF statement allows conditional execution of commands.
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When the <condition> is true, then the <command> is
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executed otherwise, the <command> is skipped.
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Examples:
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IF not exist /tmp/foo ECHO Can't find file /tmp/foo
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IF $1x == x ECHO Need at least one parameter
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IF NOT ERRORLEVEL 3 LINK $1,,;
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FOR %%<c> IN <set> DO <command>
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<c> can be any character but 0,1,2,3,..,9 (so there is no
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confusion with the %0 - %9 batch parameters).
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<set> is ( <item>* )
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The %%<c> variable is sequentially set to each member of
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<set> and then <command> is evaluated. If a member of
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<set> is an expression involving * and/or ?, then the
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variable is set to each matching pattern from disk. In
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this case only one such <item> may be in the set, any
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<item>s after the first are ignored.
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Example:
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FOR %%f IN ( *.ASM ) DO MASM %%f;
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for %%f in (FOO BAR BLECH) do REM %%f to you
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NOTE: The '%%' is needed so that after Batch parameter
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(%0 - %9) processing is done, there is one '%' left.
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If only '%f' were there, the batch parameter processor
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would see the '%' then look at 'f', decide that '%f'
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was an error (bad parameter reference) and throw out
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the '%f' so that FOR would never see it. If the FOR
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is NOT in a batch file, then only ONE '%' should be
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used.
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SHIFT
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Currently, command files are limited to handling 10
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parameters: %0 through %9. To allow access to more than
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these, the command SHIFT will perform a 'pop' of the
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command line parameters:
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if %0 = "foo"
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%1 = "bar"
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%2 = "blech"
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%3...%9 are empty
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then a SHIFT will result in the following:
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%0 = "bar"
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%1 = "blech"
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%2...%9 are empty
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If there are more than 10 parameters given on a command
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line, then the those that appear after the 10th (%9) will
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be shifted one at a time into %9 by successive shifts.
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:<label>
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This is essentially a no-op. It defines a label in the
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batch file for a subsequent GOTO. It may also be used to
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put comment lines in batch files since all lines that
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start with ':' are ignored.
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GOTO <label>
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Causes commands to be taken from the batch file beginning
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with the line after the <label> definition. If no label
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has been defined, the current batch file will terminate.
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Example:
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:foo
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REM looping...
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GOTO foo
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will produce a infinite sequence of messages:
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'REM looping...'
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NOTE: Labels are case insensitive, :FOO == :foo == :Foo
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ECHO [{ON | OFF | <message>}]
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Normally, commands in a BATCH file are echoed onto the
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standard output as they are seen by COMMAND. ECHO OFF
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turns off this feature. ECHO ON turns echoing back on.
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If ON or OFF is not specified and there is text following
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the command, that text (a message) is echoed to standard
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output. If there are no arguments at all, the current
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setting of echo (on or off) is echoed to the standard
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output in the form:
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ECHO is xxx
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Where xxx is "on" or "off".
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Redirection of standard input/standard output.
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Programs that read from the keyboard and write to the
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screen are said to be doing I/O to the standard input and
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standard output. Using any of the following will result
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in I/O to these standard devices:
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Writing to default handles 1 / read from default
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handle 0.
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Doing byte I/O using system calls 1, 2, 6-12.
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These standard devices may be redirected to/from files by
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the following in command line arguments:
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> <filename>
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causes <filename> to be created (or truncated to
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zero length) and then assigns standard output to
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that file. All output from the command will be
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placed in the file.
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< <filename>
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causes standard input to be assigned to
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<filename>. All input to the command will come
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from this file. If end-of-file is reached, then
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system calls 1, 2, 6-12 will return ^Z , while
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reading from handle 0 will return zero characters.
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>> <filename>
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causes <filename> to be opened (created if
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necessary) and positions the write pointer at the
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end of the file so that all output will be
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appended to the file.
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Note that the above will not appear in the command line
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that the program being invoked sees.
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Examples:
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DIR *.ASM > FOO.LST
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Sends the output of the dir command to the file
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FOO.LST.
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FOR %0 IN (*.ASM) DO MASM %0; >>ERRS.LST
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Sends all error output from assembling every .ASM file
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into the file ERRS.LST.
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Piping of standard I/O
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It is often useful for the output of one program to be
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sent as input to another program. A typical case is a
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program that produces columnar output that must later be
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sorted.
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The pipe feature allows this to occur naturally is the
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programs do all of their I/O to the standard devices.
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For example, if we had a program SORT that read all of
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it's standard input, sorted it and then wrote it to the
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standard output, then we could get a sorted directory
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listing as follows:
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DIR | SORT
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The | would cause all standard output generated by the
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left-hand command to be sent to the standard input of the
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right-hand command.
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If we wanted the sorted directory to be sent to a file, we
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type:
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DIR | SORT >FILE
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and away it goes.
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The piping feature is implemented as sequential execution
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of the procedures with redirection to and from temporary
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files. In the example above, the following would be an
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exact equivalent:
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DIR >/tmp/std1
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SORT </tmp/std1 >FILE
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The pipe is not a real pipe but rather a quasi-pipe
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that uses temporary files to hold the input and output as
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it sequentially executes the elements of the pipe. These
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files are created in the current directory, of the current
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drive and have the form %PIPEx%.$$$, where x will be 1 or
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2. This means that any program that runs in the pipe must
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be sure to restore the current directory and drive if it
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has changed them, otherwise the pipe files will be lost.
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VER
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Prints DOS version number.
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VOL [<drive>:]
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Prints the volume ID of the disk in drive d:. No d: does
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default drive.
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CHDIR [{<drive>: | <path>}]
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Change directory, or print current. directory.If no
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argument is given, the current directory on the default
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drive is printed. If d: alone is given, the durrent
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directory of drive d is printed. Otherwise the current
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directory is set to path.
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NOTE:"CD" is accepted as an abbreviation.
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MKDIR <path> - Make a directory.
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"MD" is accepted as an abbreviation.
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RMDIR <path> - Remove a directory.
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"RD" is accepted as an abbreviation.
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The directory must be empty except for
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'.' and '..'.
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<path> - A standard XENIX style path with the optional
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addition of a drive spec:
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A:/FOO/BAR Full path
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/FOO/BAR Full path, current drive
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FOO/BAR Current dir relative
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A:FOO/BAR " " "
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VERIFY [{ON | OFF}]
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Select/deselect verify after write mode. This supliments
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the V switch to the COPY command. Once turned ON, it
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stays on until some program changes it (via the set verify
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system call) or the VERIFY OFF command is given. If no
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argument is given, the current setting of VERIFY is
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printed to the standard output in the form:
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VERIFY is xxx
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Where xxx is "on" or "off".
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PATH [<path>{;<path>}*]
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Set command search paths. This allows users to set
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directories that should be searched for external commands
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after a search of the current directory is made. The
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default value is /bin. In addition there are two special
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cases: PATH all by itself with no arguments will print
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the current path. Path with the single argument ';' (ie.
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"PATH ;") will set the NUL path (no directories other than
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the current one searched). If no argument is given, the
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current value of PATH is printed to the standard output in
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the form:
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PATH=text of path
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or
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No path
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NOTE: On IBM systems, the default value of path is No
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path.
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EXIT
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For COMMANDs run without the P switch, this causes COMMAND
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to return. For a normal COMMAND it causes a return to
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itself.
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BREAK [{ON | OFF}]
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Like in CONFIG.SYS, "BREAK ON" turns on the Control C
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check in the DOS function dispatcher. "BREAK OFF" turns
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it off. If no argument is given the setting of BREAK is
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printed to the standard output in the form:
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BREAK is xxx
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Where xxx is "on" or "off".
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PROMPT [<prompt-text>]
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Set the system prompt. MS-DOS prompts are now user
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settable, all of the text on the command line is taken to
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be the new prompt. If no text is present the prompt is
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set to the default prompt. There are meta strings for
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various special prompts. These are of the form '$c' where
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c is one of the following:
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$ - The '$' character.
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t - The time.
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d - The date.
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p - The current directory of the default drive.
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v - The version number.
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n - The default drive.
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g - The '>' character.
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l - The '<' character.
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b - The '|' character.
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s - The ' ' character.
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e - The ESC character.
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_ - A CR LF sequence.
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EXAMPLE:
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PROMPT $n:
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Would set the normal MS-DOS prompt.
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PROMPT $n>
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Would det the normal PC-DOS prompt.
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PROMPT Time = $t$_Date = $d
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Would set a two line prompt which printed
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Time = (current time)
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Date = (current date)
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NOTE: For '$c' sequences, lower case = upper case, and
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any character not on the above list is mapped to
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nothing.
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SET (ENVNAME)=(ENVTEXT)
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Set environment strings. This command inserts strings in
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COMMAND's environment. For instance:
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SET PROMPT=$n>
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Duplicates the function of the PROMPT command.
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SET PATH=p1;p2
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Duplicates the function of the PATH command.
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SET foo=bar
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Puts the string FOO=bar into the environment (note the
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case mapping of (ENVNAME)).
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NOTE: Environments are very flexible, almost anything can
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be put into the environment with the SET command; the
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only requirement is that a single '=' be present in
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the string.
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CLS
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Clear screen, causes the ANSI escape sequence ESC[2J to be
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sent to standard output.
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CTTY /DEV/dev - Change console TTY. For instance:
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CTTY /DEV/AUX
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Would move all command I/O to the AUX port.
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CTTY /DEV/CON
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Would move it back to the normal device. The
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/dev/ prefix may be left off if AVAILDEV is
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TRUE (see configuration-file doc).
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COMMAND internal commands take path arguments.
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DIR <path>
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COPY <path> <path>
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DEL(ERASE) <path>
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If the path is a dir, all files in that dir
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are deleted.
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NOTE: The "Are you sure (Y/N)" prompt for DEL and
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ERASE now uses buffered standard input, so
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users must type a return after their answer.
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This gives them the chance to correct if they
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type 'y' by mistake.
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TYPE <path> (must specify a file)
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FILCOM - compare two files
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The FILCOM program compares two files and produces a log
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of differences between them. The comparison may be made
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in two fashions; either on a line-by-line basis, or on a
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byte-by-byte basis.
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The line-by-line compare will isolate blocks of lines that
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are different between the two files and will print the
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blocks from each file. The line-by-line compare is the
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default when neither of the two files being compared has
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the extension .EXE, .COM, or .OBJ.
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The byte-by-byte compare will display exactly which bytes
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are different between the two files. If either file being
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compared has extension .EXE, .COM, or .OBJ then the files
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will be compared in byte-by-byte mode.
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|
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RECOVER - recover files from a trashed disk.
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If a sector on a disk goes bad, you can recover either the
|
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file that contained that sector (without the sector) or
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the entire disk (if the bad sector was in the directory).
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To recover a particular file:
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RECOVER <file-to-recover>
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This will cause the file to be read sector by sector and
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to be have the bad sector skipped. Note that this implies
|
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that the allocation unit containing the bad sector will be
|
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read as much as possible. When such a bad sector is
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found, its containing allocation unit is marked as bad,
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thus preventing future allocations of that bad sector.
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|
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To recover a particular disk:
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RECOVER <drive-letter>:
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This will cause a scan to be made of the drive's FAT for
|
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chains of allocation units (files). A new root directory
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is then written that has entries of the form FILEnnnn.
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Each FILEnnnn will point to the head of one of the
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allocation unit chains.
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If there are more chains than directory entries in the
|
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root, RECOVER prints a message and leaves the un-RECOVERED
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chains in the FAT so that RECOVER can be run again once
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some room has been made in the ROOT.
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|
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DEBUG ON MS-DOS 2.0
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|
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|
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When 2.0 DEBUG is invoked it sets up a program header
|
||
atoffset 0 in its program work area. On previous versions it
|
||
was OK to overwrite this header with impunity: this is true
|
||
of the default header set up if no <filespec> is given to
|
||
DEBUG. If DEBUGging a .COM or .EXE file, however, you must be
|
||
careful not to tamper with the header of the program below
|
||
address 5CH, to do this will probably result in a crash. It
|
||
is also important that an attempt is not made to "restart" a
|
||
program once the "program terminated normally" message is
|
||
given. The program must be reloaded with the N and L commands
|
||
in order for it to run properly.
|
||
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NEW FEATURES
|
||
|
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The A (Assemble) Command
|
||
|
||
FORMAT: A [<address>]
|
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|
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PURPOSE: To assemble 8086/8087/8088 mnemonics directly into
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memory.
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o If a syntax error is encountered, DEBUG responds with
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^ Error
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and redisplays the current assembly address.
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o All numeric values are hexadecimal and may be entered
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as 1-4 characters.
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o Prefix mnemonics must be entered in front of the opcode
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to which they refer. They may also be entered on a
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separate line.
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o The segment override mnemonics are CS:, DS:, ES:, and
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SS:
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o String manipulation mnemonics must explictly state the
|
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string size. For example, the MOVSW must be used to
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move word strings and MOVSB must be used to move byte
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strings.
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o The mnemonic for the far return is RETF.
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o The assembler will automatically assemble short, near
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or far jumps and calls depending on byte displacement
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to the destination address. These may be overridden
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with the NEAR or FAR prefix. For example:
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0100:0500 JMP 502 ; a 2 byte short jump
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0100:0502 JMP NEAR 505 ; a 3 byte near jump
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0100:0505 JMP FAR 50A ; a 5 byte far jump
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The NEAR prefix may be abbreviated to NE but the FAR
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prefix cannot be abbreviated.
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o DEBUG cannot tell whether some operands refer to a word
|
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memory location or a byte memroy location. In this case
|
||
the data type must be explicity stated with the prefix
|
||
"WORD PTR" or "BYTE PTR". DEBUG will also except the
|
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abbreviations "WO" and "BY". For example:
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NEG BYTE PTR [128]
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||
DEC WO [SI]
|
||
|
||
o DEBUG also cannot tell whether an operand refers to a
|
||
memory location or to an immediate operand. DEBUG uses
|
||
the common convention that operands enclosed in square
|
||
brackets refer to memory. For example:
|
||
|
||
MOV AX,21 ;Load AX with 21H
|
||
MOV AX,[21] ;Load AX with the contents
|
||
;of memory location 21H
|
||
|
||
o Two popular pseudo-instructions have also been included.
|
||
The DB opcode will assemble byte values directly into
|
||
memory. The DW opcode will assemble word values directly
|
||
into memory. For example:
|
||
|
||
DB 1,2,3,4,"THIS IS AN EXAMPLE"
|
||
DB 'THIS IS A QUOTE: "'
|
||
DB "THIS IS A QUOTE: '"
|
||
|
||
DW 1000,2000,3000,"BACH"
|
||
|
||
|
||
o All forms of the register indirect commands are supported.
|
||
For example:
|
||
|
||
ADD BX,34[BP+2].[SI-1]
|
||
POP [BP+DI]
|
||
PUSH [SI]
|
||
|
||
o All opcode synonyms are supported, For example:
|
||
|
||
LOOPZ 100
|
||
LOOPE 100
|
||
|
||
JA 200
|
||
JNBE 200
|
||
|
||
o For 8087 opcodes the WAIT or FWAIT prefix must be
|
||
explictly specified. For example:
|
||
|
||
FWAIT FADD ST,ST(3) ; This lines will assemble
|
||
; a FWAIT prefix
|
||
|
||
FLD TBYTE PTR [BX] ; This line will not
|
||
|
||
|
||
|
||
FORMAT enhancements
|
||
|
||
FORMAT will now install volume id's during the format
|
||
process. DIR and CHKDSK will display these volume id's.
|
||
|
||
User programs can read the volume id on a particular drive
|
||
by doing a 'search next' with the volume id attribute. It
|
||
is impossible, using normal DOS calls, to delete a volume
|
||
id or to create another one. The only way to create a
|
||
volume id is to reformat the disk.
|
||
|
||
NOTE: On IBM systems the V switch must be given to FORMAT
|
||
to have it do Volume IDs.
|
||
|
||
|
||
|
||
|
||
CHKDSK FOR MS-DOS 2.0
|
||
|
||
|
||
MS-DOS 2.0 has a tree structured directory scheme which
|
||
did not exist on previous versions of MS-DOS. As a result
|
||
CHKDSK is a much more complex program than in previous
|
||
versions since it must perform a tree traversal to find all of
|
||
the files on a given disk. It employes a depth first
|
||
traversal in order to accomplish this.
|
||
|
||
Previous versions of CHKDSK automatically "fixed"
|
||
disks (regardless of whether it was appropriate). CHKDSK 2.00
|
||
run normally will not alter the disk in any way, it simply
|
||
reports on any inconsistencies found. To actually "fix" a
|
||
disk CHKDSK must be run with the F switch (Fix). This allows
|
||
you to perhaps take some alternate (to CHKDSK repairs) action
|
||
before letting CHKDSK loose on your disk.
|
||
|
||
CHKDSK 2.00 will report on non-contiguous allocation units
|
||
(extents) for specified files. This is handy for gaging how
|
||
"fragmented" a disk volume has become. This is done by simply
|
||
giving a filespec:
|
||
|
||
CHKDSK B:*.*
|
||
|
||
This would report extents for all files in the current
|
||
directory for drive B after doing a normal consistency check
|
||
on drive B. Files which have many extents can be copied and
|
||
renamed to restore them to a contiguous state, thus improving
|
||
I/O performance to the files.
|
||
|
||
Previous versions of CHKDSK would simply free
|
||
allocation units which were marked as used, but were not
|
||
actually part of any file. CHKDSK 2.00 will recover these
|
||
"orphan" allocation units if specified. If orphan allocation
|
||
units are found, CHKDSK prompts for free or recover. Free
|
||
just frees the orphans as previous versions did, recover will
|
||
employ allocation chain analysis to create "orphan files" in
|
||
the root directory of the disk. These files will have the
|
||
form "%ORPHAN%.l$$" where l will take on some ASCII value
|
||
greater than '@'. These files may then be inspected to see if
|
||
valuable data was contained in them. If there is not enough
|
||
room to make all of the "orphan" files, CHKDSK leaves the
|
||
unrecovered chains in the FAT so that CHKDSK can be run again
|
||
(once some entries in the ROOT have been deleted). NOTE:
|
||
Making ORPHAN files is a SLOW process.
|
||
|
||
Verbose mode. CHKDSK 2.00 may be run with the V switch
|
||
which causes a trace of the files and directories being
|
||
processed to be printed as CHKDSK runs.
|
||
|
||
|
||
FILTERS FOR MS-DOS 2.0
|
||
|
||
A filter is a utility that reads from standard input,
|
||
modifies the information in some way, then writes the result
|
||
to standard output. In this way the data is said to have been
|
||
"filtered" by the program. Since different filters can be
|
||
piped together in many different ways a few filters can take
|
||
the place of a large number of specific purpose programs. The
|
||
following describes the filters that are provided with MS-DOS
|
||
2.0:
|
||
|
||
CIPHER <key word>
|
||
|
||
Cipher reads a program from standard input, encrypts it
|
||
using the key word provided by the user, then writes the
|
||
result to standard output. To decrypt the file simply run
|
||
CIPHER again using the same keyword. For example:
|
||
|
||
A>CIPHER MYSTERY <NSA.CIA >SECRET.FIL
|
||
|
||
This command line will read file NSA.CIA, encrypt it using
|
||
the key word "MYSTERY", then write the result to file
|
||
SECRET.FIL To view the original file the following command
|
||
line could be used:
|
||
|
||
A>CIPHER MYSTERY <SECRET.FIL
|
||
|
||
This will read file SECRET.FIL, decrypt the file using the
|
||
key word "MYSTERY", then write the result to standard output,
|
||
which in this case is the console.
|
||
|
||
FGREP
|
||
|
||
This filter takes as arguments a string and optionally a
|
||
series of file names. It will send to standard output all
|
||
lines from the files specified in the command line that
|
||
contain the string.
|
||
|
||
If no files are specified FGREP will take the input from
|
||
standard in. The format for the command line invocation of
|
||
FGREP is:
|
||
|
||
FGREP [<option>] <string> <filename>*
|
||
|
||
The options available are:
|
||
|
||
/v Will cause FGREP to output all lines NOT
|
||
containing the specified string.
|
||
|
||
/c Will cause FGREP to only print the count of
|
||
lines matched in each of the files.
|
||
|
||
/n Each line matched is preceded by its relative
|
||
line number in the file.
|
||
|
||
The string argument should be enclosed in double quotes.
|
||
Two double quotes in succession are taken as a single double
|
||
quote. So,
|
||
|
||
A>FGREP "Fool""s Paradise" book1.txt book2.txt bible
|
||
|
||
will output all lines from the book1.txt, book2.txt and bible
|
||
(in that order that contain the string: Fool"s Paradise .
|
||
And,
|
||
|
||
A>dir b: | fgrep /v "DAT"
|
||
|
||
will output all names of the files in disk b: which do not
|
||
contain the string DAT .
|
||
|
||
MORE
|
||
|
||
The filter MORE reads from standard input, sends one
|
||
screen full of information to standard output and then pauses
|
||
with message:
|
||
|
||
-- More --
|
||
|
||
Pressing the RETURN key will cause another screen full of
|
||
information to be written to standard output. This process
|
||
continues until all the input data is read.
|
||
|
||
SORT [/R] [/+n]
|
||
|
||
Sort reads from standard input, sorts the data, the writes
|
||
the information to standard output. The sort is done using
|
||
the ASCII collating sequence. There are switches which allow
|
||
the user to select various options:
|
||
|
||
R - Reverse the sort, that is make "Z" come before "A"
|
||
|
||
+n - Sort starting with column "n" where n is some integer.
|
||
The default is start the comparisons with column 1,
|
||
this switch allows the user to start in any column.
|
||
|
||
example:
|
||
|
||
A>SORT /R <UNSORT.TXT >SORT.TXT
|
||
|
||
This command line will read the file UNSORT.TXT, do a reverse
|
||
sort, then write the output to file SORT.TXT
|
||
|
||
A>DIR | SORT /+14
|
||
|
||
This command line will cause the output of the directory
|
||
command to be piped to the sort filter, the sort filter will
|
||
sort starting with column 14 (This is the column the file size
|
||
starts), then send the output to the console. Thus a
|
||
directory sorted by file size will be the result. To get real
|
||
fancy:
|
||
|
||
A>DIR | SORT /+14 | MORE
|
||
|
||
will do the same thing except that MORE will give you a chance
|
||
to read the directory before it scrolls off the screen.
|
||
|